Non-isolated AC-DC converter having a positive output buck-boost converter and PFC at input supply
A power converter includes a battery having a positive terminal and a negative terminal, a first power input to receive AC input power, a second power input to receive DC input power from the battery, a first power output to charge the battery, a second power output to provide power to a load, a rectifier circuit coupled to the first power input, and a non-isolated single-stage power conversion circuit having an input and configured as a buck-boost converter. The power at the second power output is derived from the first power input and/or the second power input. The single-stage power conversion circuit is configured to convert an AC voltage to a DC voltage using a common energy storage element, and is coupled to the first power output and the rectifier circuit.
1. A power converter, comprising:
a battery having a positive terminal and a negative terminal;
a first power input to receive AC input power;
a second power input to receive DC input power from the battery;
a first power output to charge the battery;
a second power output to provide power, derived from at least one of the first power input and the second power input, to a load;
a rectifier circuit coupled to the first power input; and
a non-isolated single-stage power conversion circuit having an input and configured as a buck-boost converter to convert an AC voltage to a DC voltage using a common energy storage element to charge the battery, the single-stage power conversion circuit coupled to the first power output and, at the input of the power conversion circuit, to the rectifier circuit.
2. The power converter of claim 1 , further comprising a control circuit coupled to the single-stage power conversion circuit and configured to control the power conversion circuit to provide power factor correction at the first power input.
3. The power converter of claim 1 , wherein the positive terminal of the battery is coupled to the power output and the negative terminal of the battery is coupled to a neutral line of the first power input.
4. The power converter of claim 3 , further comprising a DC bus, having a DC voltage value, coupled to the input of the single-stage power conversion circuit and to the rectifier circuit, and wherein the power converter is configured to clamp an input voltage of the single-stage power conversion circuit to the DC voltage value.
5. The power converter of claim 4 , further comprising a pair of diodes interposed between the input of the single-stage power conversion circuit and the DC bus.
6. The power converter of claim 5 , further comprising a power correction factor boost converter circuit coupled to the first power input and the DC bus and configured to convert the AC input power to DC power at the DC bus.
7. The power converter of claim 3 , wherein the rectifier circuit includes a bridge rectifier.
8. The power converter of claim 7 , further comprising a capacitive element coupled to the rectifier circuit and the input of the power conversion circuit, and configured to filter an input voltage of the power conversion circuit.
9. The power converter of claim 1 , wherein the rectifier circuit includes a bridge rectifier having a positive terminal and a negative terminal, and wherein the positive terminal of the battery is coupled to the first power output and the negative terminal of the battery is coupled to the negative terminal of the rectifier.
10. The power converter of claim 9 , further comprising a capacitive element coupled to the rectifier circuit and the input of the power conversion circuit, and configured to filter an input voltage of the power conversion circuit.
11. A method of charging a battery, the method comprising:
receiving, at an input of a non-isolated single-stage buck-boost circuit, a rectified AC input voltage;
converting the rectified AC input voltage into a DC output voltage using the buck-boost circuit;
charging the battery using the DC output voltage;
providing an AC output voltage derived from at least one of the rectified AC input voltage and the DC output voltage; and
operating a plurality of switches of the buck-boost circuit to provide power factor correction at the AC power input.
12. The method of claim 11 , further comprising clamping a voltage inputted to the input of the buck-boost circuit using a DC clamp circuit.
13. The method of claim 11 , further comprising turning each of the plurality of switches off when a current through an inductor of the buck-boost circuit reaches a predetermined peak value, and turning each of the plurality of switches on when the current through the inductor is zero.
14. The method of claim 11 , wherein the plurality of switches is operated using an average current mode control to control a current in the buck-boost circuit.
15. The method of claim 11 , wherein the battery has a negative terminal coupled to a neutral line of the AC power input.
16. The method of claim 11 , wherein the battery has a negative terminal coupled to a negative terminal of the rectifier circuit.